At the end of 1901, the Wright brothers were frustrated by the flight
tests of their
1900 and
1901 gliders.
The aircraft were flown frequently up to 300 feet in a single glide. But neither
aircraft performed as well as predicted using the design methods
available to the brothers.
Based on their measurements,
the 1901 aircraft only developed 1/3 of the
lift
which was predicted by using the
Lilienthal data.
During the fall of 1901, the brothers began to question the aerodynamic
data on which they were basing their designs.
They decided to measure their own values of
lift
and
drag
with a series of
wind tunnel tests.

At the top of this page are two pictures of replicas of the
wind tunnel used in these experiments.
It was a simple, single speed, open-return design with a fan
pushing a flow of air through a long wooden box
and then exiting into the room.
The brothers ran a bicycle shop in Dayton, Ohio, and
a small gas engine was used to power the tools used in their shop.
They used a belt drive from this engine to turn the fan of
their tunnel.
Unlike modern tunnels, the brothers placed their fan at the
entrance of the tunnel. This caused swirling flow oscillations from
the fan blades to be swept through the tunnel.
The brothers worked for nearly a month to develop the
flow straightening devices
located just downstream of the fan to provide a uniform flow through
the test section.
The brothers built their own models and two
balances
to measure the
lift
and
drag
of their models. Only one balance is installed in the tunnel
at a time, but they are easily exchanged. Each model was tested on
both balances over a range of angle of attack.

To obtain data, one of the brothers would look through the view
window on the top of the tunnel and record the angles on the
balance output dial in the test section.
The brothers built models of their wing designs using materials available
in their bike shop. Strips of 20 guage steel (1/32 inch thick) were
cut, hammered, filed and soldered to produce various shapes.
They made between one and two hundred models and
made quick preliminary tests in
October, 1901, to develop their
test techniques
and to investigate a wide range of design variables.
Some of the models were used in combination to study bi- and tri-wing designs.
Following the preliminary experiments, they chose about 30 of their
best designs for more detailed
parametric studies.
In these experiments,
only one design variable was changed between models.
You can duplicate the wind tunnel tests of the Wright brothers
by using our interactive
wind tunnel simulation.

At the end of their 1901 wind tunnel tests, the Wright brothers had the most
detailed data
in the world for the design of aircraft wings. In
1902, they returned to Kitty Hawk with a new
aircraft based on their new data.
This aircraft performed much better than the 1901 aircraft and lead directly
to the successful
1903 flyer.
Results of the wind tunnel tests were also used in the design of their
propellers.